fix(500): the hooks decode a \u escape to UTF-8 in any locale and any awk

scribe_json_unescape wrote each escaped code point with sprintf("%c", n),
which writes the character only under gawk in a UTF-8 locale; gawk in the C
locale and mawk in any locale write the single byte n % 256. The server
escapes every non-ASCII character, so "·" reached the session as 0xB7, "—"
as 0x14 and an emoji as a NUL wherever a hook ran without a UTF-8 locale.
The decoder now encodes UTF-8 itself under LC_ALL=C. A new test sends what
the server sends from a bare environment, in three locales (#5495).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

plugin/.claude-plugin/plugin.json

@@ -1,7 +1,7 @@
 {
   "name": "scribe",
   "description": "Scribe for Claude Code: connects the scribe MCP server, adds the hooks that deliver live project state and relevant records at the right moment, ships the shared client-neutral Scribe skills (using-scribe, writing-plans, reporting-back, systematic-debugging, verification, brainstorming, reusing-code, shape-accounting, family-canon), and syncs your saved Scribe Processes as skills (/scribe:sync).",
-  "version": "2026.10.09.1845",
+  "version": "2026.10.09.1850",
   "author": {
     "name": "Bryan Van Deusen"
   },